It is not unusual for a typical south american meal to be high in carbs. Many traditional dishes such as sancochos will contain a variety of high carb veggies and will be served along with a plate of white rice and plantains. Some pasta dishes may also be accompanied by rice. If high carbs are not your thing, you would be better off ordering off the menu and asking for specific menu items, such as a soup accompanied by perhaps a salad, hold the rice. You can also order certain grilled meats/poultry/fish the same way. Most restaurants are very accommodating, and there is usually staff on hand that speaks English well enough if your spanish is not up to par.
I would say that Seba Seba is the equivalent of your typical hispanic diner. Food and service are O.K., and the price reflects that. For a step above and still inexpensive, try La Nueva Cafe on 37th and 86th Street. Their bakery, located up the street, offers great baked meat, chicken, cheese and spinach empanadas for only $1.50. They're quite delicious! They offer good food at a decent price, and the service is friendly. Some wine is available, and they will be more than happy to provide you with a glass of water!